Bonding apparatus are used in semiconductor assembly and packaging. An example of a bonding apparatus is a wire bonder, which makes electrical wire connections between electrical contact pads of semiconductor chips and a substrate—a process which is known as wire bonding. Specifically, bonding wire is fed from a wire spool to a bonding tool (e.g. a capillary) to make the electrical wire connections between the semiconductor chips and the substrate during wire bonding.
One method of wire bonding uses a ball bond and involves a series of steps, as follows: i) melting a length of bonding wire held by the capillary to produce a free air ball; ii) lowering the free air ball to an electrical contact pad of a semiconductor chip; and iii) welding the free air ball to the substrate via a ball bond. The capillary then draws out a loop of the bonding wire starting from the ball bond and ending with a wedge bond to electrically connect the semiconductor chip with the substrate.
Before the wire bonding process begins, the semiconductor chip is bonded to the substrate using an adhesive die attach material such as epoxy. If the semiconductor chip has not been properly adhered to the substrate, the semiconductor chip may detach from the substrate during wire bonding to cause a bonding failure, especially when the capillary is drawing out a loop of the bonding wire to electrically connect the semiconductor chip with the substrate. In this case, the detached semiconductor chip would interfere with the wire bonding process and prevent the wire bonder from continuing its operation. This results in undesirable machine downtime of the wire bonder.
In order to recover the wire bonder from the bonding failure to resume a normal operating state for semiconductor chip fabrication, a technician has to manually remove the detached semiconductor chip from the wire bonder. In addition, the technician may be required to form a dummy bond between the bonding wire and the substrate, and to manually adjust a tail length of the bonding wire through the capillary, before the wire bonder can continue operating.
Thus, it is seen that the conventional way of recovering the wire bonder from the bonding failure is not just labour intensive, but also time-consuming. Such a solution naturally reduces the throughput capacity of the wire bonder for wire bonding.
Accordingly, it is an object of this invention to seek to provide a solution for recovering a bonding apparatus to resume a normal operating state for semiconductor chip fabrication in the event that a semiconductor chip is detached from a substrate during wire bonding.